1. Field of the Invention
The invention relates to a vehicle in which wheels are driven by motors, such as an electric automobile.
The invention also relates to a vehicle driving device provided with drive motors that drive first wheels and second wheels, respectively, and to an electric vehicle equipped with the vehicle driving device.
2. Description of Related Art
Electric vehicles using an in-wheel motor system in which a motor driving a wheel is disposed inside the wheel have been disclosed. Among them, there are electric vehicles using a direct drive system by which a wheel is driven by a motor directly connected to the wheel (see, for example, Japanese Patent Application Publication No. 2011-188557 (JP 2011-188557 A)).
In such an electric vehicle, a torque necessary when the vehicle is driven is distributed to front-wheel motors driving the front wheels and rear-wheel motors driving the rear wheels in order to minimize the total power consumed by all of the motors. Thus, in the electric vehicle, the torque that can be efficiently outputted by the front-wheel motors is combined with the torque that can be efficiently outputted by the rear-wheel motors to output the torque necessary when the vehicle is driven.
A vehicle driving device has a configuration in which two first drive motors that drive a pair of respective first wheels and two second drive motors that drive a pair of respective second wheels are contained in respective first wheels and second wheels. The vehicle driving device distributes the torque when the electric vehicle is driven to the first drive motors and second drive motors so that the total power consumed by all of the drive motors is minimized. Thus, the vehicle driving device combines the torque at which the individual efficiency of the first drive motor is increased and the torque at which the individual efficiency of the second drive motor is increased to output the torque necessary when the electric vehicle is driven. JP 2011-188557 A shows an example of such a vehicle driving device.